Authorities believe Ready was the gunman in a mass murder-suicide on May 2 at a house in a suburb east of Phoenix. Investigators have said the massacre was a family argument that turned deadly when Ready opened fire on his girlfriend, her daughter, her daughter's boyfriend and her daughter's toddler before killing himself.
In the story the New Times published last week, journalist Stephen Lemons said Heppler first came to him with the concerns. But because the information involved potential harm to people's lives, the journalist referred Heppler to a local cop, who in turn sent him to the FBI.
"Heppler agreed to become an informant (he says he was not paid) and agreed to wear a recording device and allow his phone to be tapped," Lemons wrote.
Heppler told the newspaper, however, that he ended up having a fallout with the FBI after he blew his cover as a secret informant to one of Ready's associates.
It's unclear how credible Heppler's claims were or how seriously the FBI took him. However, in an interview days after this month's massacre, James Turgal, the lead agent in the FBI's Phoenix office said investigators were looking at Ready as part of an ongoing domestic terrorism probe at the time of the killings.
Turgal said the agency was looking into possible shootings of immigrants in the desert as part of its investigation. Meanwhile, authorities in southern Arizona said last week they investigated Ready but ultimately cleared him in the killing of two immigrants north of Tucson. They said they believe the killings were the work of bandits or a rival smuggling cartel.
Ready was a longtime member of the National Socialist Movement, the largest neo-Nazi organization in the nation. In recent years, he founded a group called the U.S. Border Guard, which organized armed patrols in the Arizona desert. The group would search for immigrants and frequently hold them at gunpoint until legitimate law enforcement would arrive.
Ready also advocated for landmines to be used along the U.S.-Mexican border as a form of immigration control. At the scene of the massacre, federal authorities discovered at least six military-grade projectile grenades that were designed to pierce armor.